1. Field of the Invention
The present invention relates to an embedded circuit board having chips of different thicknesses embedded in a first Copper Clad Laminate (CCL), and a second CCL is provided to allow the chips to level with the first CCL, and a manufacturing method thereof.
2. Description of the Related Art
In general, as electronic products become more highly functional, more lightweight and smaller in size, an increased mounting density is being regarded as an important factor.
With the tendency toward miniaturization, various technologies for mounting a larger number of packages on a board with a limited size have been developed and proposed, to improve mounting density of resistors, chips, Integrated Circuit (IC) parts and other components that are inserted onto the board.
In most cases, individual resistors, chips or ICs are mounted on the surface of a printed circuit board, with resistors and IC parts inserted into an inner layer of a board by using new material and processes to substitute for the role of passive and active parts of chips mounted on the surface of a board.
As shown in FIGS. 1 to 3, in a conventional embedded printed circuit board 1, a CCL 2 is formed with a cavity 4 into which IC parts 3 are inserted, a tape 5 is attached to one side of the CCL 2 to fix the IC parts 3, and the CCL 2 is turned over so that the IC parts 3 are pressed into the cavity 4.
In general, IC parts 3 having the same height as that of the cavity 4 are used. However, when the IC parts 3 having different thicknesses are embedded, as often required, Polypropylene Glycol (PPG) A1 is cut to an appropriate height and placed on the IC parts 3 having a thin thickness to level with the cavity 4, a Resin Coated Copper foil (RCC) 6 containing resin 6a is located on the CCL 2 for the lamination of another layer, and heat compression is performed, as shown in FIGS. 1 and 2.
However, as shown in FIGS. 2 and 3, in the conventional embedded printed circuit board 1, since the resin 6a contained in the RCC 6 flows out and fills the cavity 4 during a lamination process, the IC parts 3 eccentrically move from the initial position due to the resin 6a. Therefore, in the subsequent process, a via hole of the RCC 6 connected to a pad of the IC parts 3 is not exactly formed, causing a defect.
Furthermore, when heat is generated from the IC parts 3, additional components required to discharge the heat because the thickness of the IC parts 3 is thin, resulting in an increase in the manufacturing cost. In addition, it is necessary to provide a separate routing layer to perform an Electro Magnetic Interference (EMI) shield function.
In this regard, it is necessary to provide another CCL to prevent eccentric movement of chips by allowing resin to be uniformly introduced into the cavity in the CCL in the lamination process.